Compound Interest Calculator

See how compound growth and consistent monthly contributions turn modest savings into life-changing sums over 10, 20, or 30 years.

How to use this calculator

Compound interest is the closest thing in finance to a free lunch. Every dollar of return gets reinvested, then earns its own return next period, and so on. The math is unforgiving in both directions - which is why a credit-card balance growing at 24% APR can outrun your payments, but a 401(k) returning 8% can quietly become a million dollars.

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